ibus-hangul Bug 494445 requires a hotkey of "press the right Alt button and release it without hitting other buttons simultaneously" to switch between Hangul and English input modes. Implementing a mode in ibus-hangul would take too much time before Fedora 11, so we agreed to add a temporary workaround making right-Alt a global trigger hotkey in ibus instead.
Unfortunately, it seems it doesn't work properly.
* Alt_R by itself works, which triggers upon any (release?) event. Unfortunately, it also triggers when you don't want it, like Alt_R+F in gedit.
* Release+Alt_R is supposed to work to isolate it as press-and-release hotkey, except it doesn't. According to phuang other keys work in this manner with ibus, but not Alt.
In any case, both the proper fix for ibus-hangul and the ibus global trigger workaround require Alt + Release isolation to be fixed.
This is a F11Blocker, unless we decide that Bug 494445 cannot be fixed before F-11.